The technology which enables the user to gain access to interactive services is known in the prior art, in the realm of digital television. These services are either provided by the digital television manufacturer, or by outside companies. The services may be built into the television set or may be transferred from outside, to the television, by means of an application and then subsequently executed. Several services may be used at the same time. An application is a particular use of information technology which makes it possible in particular to offer a service. An application manager is in charge of managing all these services. There is a particular application, referred to as the navigator, commonly provided by the digital television manufacturer which enables the user to drive the various applications and hence to navigate around the services. The navigator and the application manager exhibit tight links. The navigator is commonly activated by means of a remote control furnished with a means of selection. The navigator makes it possible in particular to gain access to the various services such as those for choosing favorite interactions, favorite stations or outside services communicated for example by satellite or by cable, etc.
At present the display screen is shared between the various interactive services and the navigator. When it is activated, the navigator appears on the screen, masking a certain part of the graphics area. The representations of the applications are defined in the applications data, these representations may be located in the part masked by the navigator and may no longer appear. The navigator may also mask a part of the representation of the video signal. One solution may be to reduce the size of the video display. However, in this case the position and the size of the representation of the applications are no longer complied with relative to that of the representation of the video signal. The representation of the applications may moreover be masked.
To remove the risk of having the representation of applications which are poorly placed or poorly dimensioned, the following solutions exist at present:                The navigator covers the whole of the screen, but in this case the user can no longer view on screen the representation of the applications.        When the size and the position of the video signal are modified, a cue comes to the applications to resize the size and the position of their on-screen representation. This assumes the provision of an interface for programming complex applications. This interface must be compatible with the services developed. This solution has flaws. Firstly that of being limited to services which are compatible with the interface for programming applications, next that of making errors in programming. Moreover, certain applications present difficulties in being resized and therefore require additional programming as well as a memory of larger size.        
A first object of the invention is to provide a process for a display screen allowing the sharing of the screen area between the representations of the various services and of the navigator and such that the proportions and the positioning of the on-screen representations of the applications relative to the on-screen representation of the video signal are preserved.
A second object of the invention is to provide a device for a display screen such that the representation of the navigator does not mask either the representation of the applications or that of the video signal.
According to the invention, if the area of the screen for viewing the video signal is reduced by the screen area required for displaying the navigator, the representation of the applications is automatically resized and repositioned as a function of the new area available for the representation on the screen for viewing the video signal and the applications. The user therefore observes a homothetic reduction on the screen of the depiction of the video signal and of the representation of the applications relative to the space occupied on the screen with the video signal in a situation of maximum area of representation. If the user exits the navigator, then the on-screen depiction will represent on the entire area of the screen the representation of the video signal as well as the representation of the applications.